Assemblies, systems, and methods for vacuum assisted internal drainage during wound healing

ABSTRACT

Assemblies, systems, and methods convey fluid from an internal wound site or body cavity by applying negative pressure from a source outside the internal wound site or body cavity through a wound drain assembly that, is placed directly inside the internal wound site or body cavity.

RELATED APPLICATION

This application is a continuation-in-part of copending U.S. patentapplication Ser. No. 12/661,293, filed Mar. 15, 2010, which is acontinuation of U.S. patent application Ser. No. 11/810,027, filed Jun.4, 2007 (now U.S. Pat. No. 7,699,831), which is a continuation-in-partof U.S. patent application Ser. No. 11/646,918, filed Dec. 28, 2006,which claims the benefit of U.S. Provisional Patent Application Ser. No.60/810,733, filed Jun. 2, 2006, which are each incorporated herein byreference.

FIELD OF THE INVENTION

This application relates generally to the drainage of fluid from thebody during the wound healing process, e.g., following surgery, trauma,or placement of implants or surgical devices.

BACKGROUND OF THE INVENTION

During surgery, or as a result of trauma, subcutaneous tissue can beremoved or altered, and an open void or dead space or cavity is createdwithin the tissue that was previously attached to other tissue. This mayalso occur inside the chest or abdominal cavity. The very small bloodand lymphatic vessels that previously ran from the underlying tissue(i.e., muscle, connective tissue) to the overlying tissue (i.e., skin,muscle) can be cut or damaged. When this occurs, the natural process ofwound healing is triggered.

The process of wound healing is well known. When an initial incision ismade at the beginning of a surgical procedure, or following a traumaticwound, the body conveys blood, blood products, and proteins into thecavity or void or operative dead space that is formed. A wound exudatebegins to form. This initiates the first stages of wound healing.

The production of wound exudate occurs as a result of vasodilationduring the early inflammatory stage of wound healing. It occurs underthe influence of inflammatory mediators, such as histamine andbradykinin. Wound exudate presents itself as serous fluid in the woundbed.

Wound exudate is part of normal wound healing in acute wounds. Woundexudate contains proteins and cells that are vital to both initiate andpropagate the healing process. The constituents of wound exudateinclude, inter alia, (i) fibrin (function: clotting) ; (ii) platelets(function: clotting); (iii) other cellular elements, e.g., red bloodcells and white blood cells including, lymphocytes, neutrophils andmacrophages; and (iv) wound debris/dead cells.

The blood cells, blood products, and proteins within the wound void orcavity initiate the coagulation cascade. The blood inside the void oroperative dead space mixes with the proteins and begins to form clot.Fibrin forms from fibrinogen, and the process of clotting and woundhealing is initiated. The coagulation cascade begins immediately afterincision or injury, and typically continues until about the fifth toseventh day of wound healing. The end result of the coagulation cascadeis the formation of thrombus and clot. It is this natural clottingprocess that avoids exsanguination, else the person would bleed todeath.

Thus, as part of the normal wound healing process, it is to be expectedthat fluid collecting in the wound void will include wound exudate,blood cells, blood products, blood clots, thrombus, wound debris, deadcells, and other byproducts of wound healing. The larger the operativedead space, the greater is the potential for internal fluid collection.

Due to the progression of the wound healing process, it is well knownthat the constituency of the fluid within the operative space changesover time. In the early stages of wound healing, as the byproducts ofwound healing form, the fluid is bloody and viscous. Only after woundhealing progresses, and the coagulation cascade advances to repair theinjury, does the fluid in the wound void turn less bloody and viscous,into a straw-colored serum. Anyone having surgery where a drain isplaced has experienced the fluid changing from a thick bloody drainageto a more clear yellow or serous color.

A person who is in good health, or has minimal skin undermining or hasotherwise undergone a minor procedure, can resolve the accumulation offluid within a wound void over time. However, the body still has fluidthat collects in the open space. This open space needs to fill with theexudates, which facilitates closure of the dead space, approximation ofthe tissues, and normal healing. Wound healing also needs to beaccompanied by an absence of continued irritation, so that there is nota continuous initiation of new wound healing.

Currently, to aid the evacuation of fluid from the wound, conventionalwound drains are placed at the end of a surgical procedure.

There is a recognized problem with conventional wound drain technology,which is directly related to the nature of the wound healing processitself. Effective wound drainage necessarily requires the ability toclear the byproducts of the wound healing process, as described, such aswound exudate, blood cells, blood products, blood clots, thrombus, wounddebris, dead cells and other viscous materials However, experiencedemonstrates that these naturally occurring byproducts of wound healingplug conventional wound drains. As a result, current wound draintechnology is not effective at adequately clearing wound voids.Concurrently, current drains are ineffective at formally closing downlarger dead spaces, and can only manage small amounts of fluid directlyaround the drain itself. Fluid can quickly overwhelm the space andcollect to large volumes, creating a seroma and preventing the tissuesurfaces from approximating and healing. Finally, conventional wounddrains provide non-uniform blood and fluid removal with low inconsistentsuction pressure, often with long drain duration and the potential ofinfection. The wound void is not closed down, and seroma formationremains high and persistent.

As a result, seromas commonly develop following drain removal or whenfluid is produced at a greater rate than can be absorbed. Conventionalwound management techniques are commonly applied when a seroma becomes aclinical concern. Placement of a seroma catheter or additional drain, aswell as repeated or serial drainage of a seroma, may be required, whichinvolved recurrent, serial punctures often over two to three weeks,until the seroma cavity is closed or is no longer a clinical problem.

Another option is to place a “Seroma Cath”™. A clinically accepted wayto deal with a seroma that does not appear to be resolving on its own,is to replace a new surgical that continuously drains the space system,coupled with treatment with antibiotics to prevent infection while thecurrent drain system is in use. There are currently numerous types ofwound drains on the market, most of them utilizing some form of tubingto withdraw fluid from the wound until the body can resorb the fluidwithout assistance. A continuous drain system allows the fluid tocontinuously escape until the body can complete the healing process onits own.

A representative prior art continuous drain system can comprise animplanted device such as a piece of rubber tubing (Blake Drain) (asshown in FIG. 1), which provides dependent gravity drainage or respondsto a negative suction force generated by a manual closed suction bulb.These types of drains constitute the most common devices currentlyavailable. The problem with these devices is that they may becomeplugged by blood clots carried by the wound fluid, or may be overwhelmedby the fluid generated in the space, or may have such low continuouspressure that they are ineffective at closing the internal space down.So pervasive is the problem of plugging and seroma formation withconventional wound drains that the Home Care instructions for using thedrains include instructions for “stripping or milking” the drains whenclots need to be cleared from the drains. Further, although they may,when not plugged, drain fluid, fluid drainage is limited to fluiddirectly around the drain itself. As a result, current drains again, atbest, do not effectively clear all of the fluid in the space and, moreimportantly, they do not clear enough fluid to effectively seal down andclose off the dead space. In essence, any fluid in the dead spaceeffectively blocks the tissues from approximating or coming Into contactwith each other preventing or delaying the normal wound healing process.

Another representative prior art continuous drain system, which iscurrently approved for external use only, can take the form of anexternally applied device comprising a piece of foam with an open-cellstructure, which coupled to one end of a plastic tube (see FIG. 2). Thefoam is placed externally on top of the wound or skin, and the entireexternal area is then covered with a transparent adhesive membrane,which is firmly secured to the healthy skin around the wound margin. Theopposite end of the plastic tube is connected to a vacuum source, andfluid may be drawn from the wound through the foam into a reservoir forsubsequent disposal. This prior art system has been called a “VacuumAssisted Closure Device” or a VAC device. Conventional VAC devices,however, are only approved and used for external wounds. ConventionalVAC devices are not approved or used for internal wounds or operativesites, and may create bleeding upon withdraw and leave particulatematter from the foam inside the wound base.

Current wound drain devices assemblies at times do not remove asubstantial amount of fluid from within a wound and have otherperformance issues. For example, external VAC devices clear fluiddirectly around external wounds (as FIG. 3 shows), and they are limitedto the application to external wounds only. They leave the remainder ofthe wound site or operating space open, which must be allowed to heal inon its own by “secondary intention,” or closed surgically at anotherpoint in time.

Furthermore, the clinical use of external VAC devices may not make wounddrainage more cost-effective, clinician-friendly, and patient-friendly.

For example, the foam structures and adhesive membranes associated withconventional practices of external VAC need to be periodically removedand replaced. Currently, dressing changes are recommended every 48 hoursfor adults with non-infected wounds, and daily for infants andadolescents. Current techniques place, the foam material in directcontact with granulating tissue. Removal of the foam structures in thepresence of granulating tissue and the force of pressure on the woundbed that this removal can cause pain or discomfort. The foam sponge canalso de-particulate and remain in the wound. Furthermore, the multiplesteps of the conventional external VAC procedure—removing the adhesivemembrane, then removing the old foam structures, then inserting the newfoam structures, and then reapplying the adhesive member along theentire periphery of the wound—are exacting, tedious and time consuming.They only prolong pain or discomfort, and cause further disruption tothe patient, and also demand dedicated nursing time and resources.

Furthermore, to function correctly, the adhesive membrane applied overthe foam wound structures must form an airtight seal with the skin.Obtaining such a seal can be difficult, particularly in body regionswhere the surrounding skin is tortuous, and/or mucosal and/or moist.

Furthermore, prolonged wearing of wet dressings can cause furtherbreakdown and maceration of the surrounding skin thereby increasing thewound size. This can cause further discomfort to the patient, and theexudate can often be offensive in odor and color causing furthermorbidity to the patient. This may, in turn, require more numerousdressing changes and re-padding throughout the day, which is disruptiveto the patient and costly both in terms of nursing time and resources.

Furthermore, since the membrane and the material of the foam structuresare both in direct contact with tissue, tissue reactions can occur.

A seroma or fluid collection in closed interior wounds is by far themost common complication in surgery today. Such complications result ina significant amount of lost income to patients, as well as expenses toinsurers and physicians who have to care for these patients that requireserial drainage. Such complications also delay wound healing, may entailadditional surgical procedures, and ultimately delay the patient'sreturn to work and routine functional activity. Seroma management canalso be costly and, further, can place health care workers to additionalneedle exposure risks and related outcomes such as hepatitis, etc.Concurrently, there are millions of dollars being spent on developinginternal glues to try to get internal tissues, separated by surgery, toadhere back together following surgery.

The inability to prevent or treatment seromas that form in closedinterior wounds is a problem that has persisted in the field of electivesurgery since the beginning of surgery, and has been documented in thesurgical literature for all specialties over the last fifty years.Seromas and abnormal fluid collection are so common, that physicians andsurgeons will acknowledge that seromas are, unfortunately, an expectedpart of wound healing following surgery.

However, it does not have to be this way.

SUMMARY OF THE INVENTION

The invention provides a solution to the persistent, unsolved clinicalproblem of seromas, and, beyond that, makes it possible to actuallyclose down a dead space or surgical wound, to approximate tissues sothat a seroma cannot form, thereby accomplishing what current wounddrains fail to do.

The invention provides assemblies, systems, and methods for draining awound that is created by surgery or trauma. The wound is defined by aninterior dead space having a volume enclosed between interior tissuesurfaces consisting of muscle, connective, or skin tissue containingblood vessels that have been separated by surgery or trauma within abody beneath substantially intact skin. As part of the natural woundhealing process, extracellular exudates comprising blood, serous fluid,and byproducts of wound healing including blood clots can accumulateduring wound healing. The invention provides assemblies, systems, andmethods that do not only manage blood and fluid collection of theextracellular exudates in the interior dead space, but also serve toclose and eliminate the dead interior space itself, by drawing theseparated interior tissue surfaces together to promote adherence of thetissue surfaces and a norm aa wound healing process.

One aspect of the invention provides a wound drain assembly andassociated systems and methods comprising at least one housing that issized and configured for placement substantially entirely within theinterior dead space. The housing encloses an open interior. The wounddrain assembly also includes perforations in the housing communicatingwith the open interior. The perforations are sized and configured topass the extracellular exudates without substantial plugging. The wounddrain assembly further includes tubing coupled to the open interior andextending outside the interior dead space. The tubing is sized andconfigured to be coupled to a source of negative pressure outside theinterior dead space. The wound drain assembly also includes an open cellcomponent, e.g., gauze or open cell material or sponge foam material,carried within the open interior to take in (e.g., by adsorption and/orabsorption) extracellular exudates passed into the housing through theperforations, and to transmit the extracellular exudates into the tubingfor discharge. The wound drain assembly may comprise a nonabsorbableconstruct, or may comprise a material that is absorbed over time by thebody, or combinations thereof.

In one embodiment, the perforations comprise slits or slots that emulatea one-way valve. The emulated one-way valve is normally substantiallyclosed in the absence of applied negative pressure. When substantiallyclosed, tissue in-growth through the perforation is prevented. Theemulated one-way valve is opened in response to applied negativepressure to pass the extracellular exudates without substantialplugging. In one arrangement, the perforations in the housing compriseat least one “x”-shaped slit. In one arrangement, the perforations inthe housing comprise at least one semilunar-shaped slot. Other geometricflap designs may be used.

In one embodiment, the perforations comprise a mean pore diameter ofabout 0.5 mm to about 5 mm to pass the extracellular exudates withoutsubstantial plugging. In one embodiment, the housing, the perforations,and open cell component are mutually sized and configured, while theextracellular exudates token in by the open cell material are conveyedin response to the negative pressure from the wound, to draw togetherthe separated interior tissue surfaces, thereby promoting adherence ofthe tissue surfaces and a normal wound healing process, effectivelyclosing the operative dead space.

Another aspect of the invention provides a system that includes a wounddrain assembly. The wound drain assembly comprises a housing enclosingan open interior. The housing is sized and configured for placementwithin an interior wound site or body cavity. Perforations in thehousing communicate with the open interior, and an open cell componentis carried within the open interior to take in fluid in the interiorwound site or body cavity. Tubing is coupled to the open interior andextends outside the interior wound site or body cavity. The tubing issized and configured to be coupled to a source of negative pressureoutside the body cavity to convey fluid taken in by the open cellcomponent from the internal wound site or body cavity. The systemfurther includes a tubular sleeve including a tissue penetrating distaltip for accessing the interior wound site or body cavity and an interiorbore sized and configured to accommodate passage of the wound drainassembly into the accessed interior wound site or body cavity.

Another aspect of the invention provides families of wound drains, eachfamily comprising at least one wound drain assembly. Within each family,the wound drain assembly/assemblies possess dimension(s) sized andconfigured to fit the particular morphology of an interior dead spacecreated by a particular application or surgical procedure. For example,one family of wound drain assemblies can be provided specially sized andconfigured for conveying extracellular exudates from an interior deadspace resulting from procedures creating larger wound voids, typicallybut not confined to reconstructive surgery, orthopedic surgery, orprocedures like tummy tucks or abdominoplasty. On the other hand,another family of wound drain assembles can be provided specially sizedand configured for conveying extracellular exudates from an interiordead space resulting from procedures created smaller wound voids such ashernia surgery, pediatric surgery, neurosurgery, or cosmetic surgery.Within each family, the wound drain assemblies include housings thatenclose an open cell component and that are perforated for conveyingextracellular exudates from the, particular interior dead space, withoutsubstantial plugging, in response to the application of negativepressure. The housings and open cell components may be of differentdimensions to account for the various surgical applications.

Another aspect of the invention provides a wound drain assembly andassociated systems and methods in which there are at least two housingsin fluid communication in a serial, spaced apart relationship. Thehousings enclose an open call component and are perforated for conveyingextracellular exudates from an interior dead space, without substantialplugging, in response to the application of negative pressure. In use, aserial (i.e., in-line) internal drain system can be placed, dependingupon the morphology of a given wound. void, along the axis of alongitudinally elongated wound void (e.g., as a result of spinal fusionsurgery), or from front to back within a wound void that extends atleast partially in anterior and posterior, or circumferential, aspects(e.g., as a result of abdominoplasty or total joint replacement surgeryor spinal surgery where an elongated, serial device would be beneficialor where two or more drains would typically be required), or a woundsite that requires, e.g., drainage both inside and outside the abdomen.

Another aspect of the invention provides a wound drain assembly andassociated systems and methods in which there are at least two housingsin fluid communication in a parallel relationship. The housings enclosean open cell component and are perforated for conveying extracellularexudates from an interior dead space, without substantial plugging, inresponse to the application of negative pressure. In use, the parallel(i.e., branched) internal drain system cart be placed from front to backwithin a wound void that extends at least partially in anterior andposterior, or circumferential, aspects (e.g., as a result ofabdominoplasty or total joint replacement surgery), or a wound site thatrequires e.g., drainage both inside and outside the abdomen.

Another aspect of the invention provides a wound drain assemblycomprising a wound drainage structure comprising a material capable ofbeing absorbed by the body and being sized and configured to take influid in an interior wound site or body cavity. The assembly includestubing coupled to the wound drainage structure and extending outside theinterior wound site or body cavity. The tubing is sized and configuredto be coupled to a source of negative pressure outside the body cavityto convey fluid taken in by the material from the internal wound site orbody cavity. In one embodiment, the absorbable wound draining structureis sized and configured, while the fluid taken in by the material isconveyed in response to the negative pressure from the wound, to drawtogether separated interior tissue surfaces, thereby promoting adherenceof the tissue surfaces and a normal wound healing process, effectivelyclosing the interior wound site or body cavity.

Another aspect of the invention provides system comprising an absorbablewound drain assembly. The system includes a tubular sleeve including atissue penetrating distal tip for accessing the interior wound site orbody cavity and an interior bore sized and configured to accommodatepassage of the wound drain assembly into the accessed interior woundsite or body cavity.

The assemblies, systems, and/or methods that embody the technicalfeatures of the invention apply a vacuum of significant negativepressure internally and directly in a wound void or body cavity forenhanced wound healing benefits. By applying a vacuum of significantconsistent negative pressure internally and directly in the wound voidor body cavity, the assemblies, systems, and/or methods reduce the“dead-space” or open area inside the wound or cavity. The assemblies,systems, and/or methods increase the nature and extent of wounddrainage, promote tissue adherence, facilitate closure of wounds, andthus decrease seroma formation and promote primary wound healing. Theassemblies, systems, and/or methods thereby decrease the costly andincreased patient. morbidity caused by seroma formation and theresultant delay in primary wound healing or need for additional surgicalprocedures or drainage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an anatomic side section prior art view of a human abdomenshowing an interior wound void and a tube that is placed according toconventional techniques to drain fluid from a seroma at the wound site.

FIG. 2 is an anatomic side section prior art view of an exterior woundvoid showing an external VAC device placed according to conventionaltechniques to drain fluid from a seroma only at an external wound site.

FIG. 3 is an anatomic, somewhat diagrammatic prior art view of thelimited drainage area achieved by the external VAC device shown in FIG.2.

FIG. 4A is an anatomic side section view of a human abdomen, like thatshown in FIG. 1, but showing a drain system that embodies features ofthe invention, comprising an internally placed wound drain assemblycoupled to an external source of negative pressure to conveyextracellular exudates from the wound.

FIG. 4B is an anatomic side section view of the human abdomen, as showin FIG. 4A, showing the drain system that embodies features of theinvention serving, while the extracellular exudates are conveyed inresponse to the negative pressure from the wound, to draw together theseparated interior tissue surfaces, thereby promoting adherence of thetissue surfaces and a normal wound healing process.

FIG. 5 is an anatomic, somewhat diagrammatic view of the enhanceddrainage area achieved by the drain system. shown in FIGS. 4A and 4B.

FIG. 6 is a perspective, exploded view of a representative embodiment ofa wound drain assembly of the type shown in FIGS. 4A and 4B.

FIGS. 7A and 7B are enlarged views of representative forms of open cellmaterial comprising a sponge foam material that the wound drain assemblyshown in FIG. 6 may carry.

FIG. 8 is a perspective, assembled view of the wound drain assemblyshown in FIG. 6.

FIGS. 9 to 13 are perspective views of other representative embodimentsof a wound drain assembly of the type shown in FIGS. 4A and 4B.

FIGS. 14 and 15 are representative views of various systems of a typeshown in FIGS. 4A and 4B.

FIGS. 16 and 17 show, respectively, a wound drain assembly of the typeshown in FIGS. 4A and 4B before and during the application of negativepressure.

FIG. 18 shows, in an anatomic view, a system like that shown in FIGS. 4Aand 4B, comprising a wound drain assembly coupled to a portable sourceof negative pressure that can be carried by an individual, but also befixed or attached to a wall section.

FIGS. 19A, 19B, and 19C show, in an anatomic view, a system like thatshown in FIGS. 4A and 4B, comprising an absorbable would drain assembly.

FIG. 20A is another representative embodiment of a wound drain assemblythat can be used in the manner shown in FIGS. 4A and 4B.

FIG. 20B is a section view of the wound drain assembly taken generallyalone line 20B-20B in FIG. 20A.

FIGS. 20C and 20D are enlarged views of a portion of the wound drainassembly shown as 20C in FIG. 20A, showing a perforation in the housingthat has been slotted or slotted into an x-shape to emulate a one-wayvalve, FIG. 20C showing the emulated valve in a substantially closedcondition and FIG. 20D showing the emulated valve in an openedcondition.

FIG. 21A is another representative embodiment of a wound drain assemblythat can be used in the manner shown in FIGS. 4A and 4B.

FIGS. 21B and 21C are enlarged views of a portion of the wound drainassembly shown as 21B in FIG. 21A, showing a perforation in the housingthat has been slotted or slotted into a semi-lunar shape to emulate aone-way valve, FIG. 21B showing the emulated valve in a substantiallyclosed condition and FIG. 21C showing the emulated valve in an openedcondition.

FIGS. 22A, 223 and 22C are, respectively, a perspective top view, sideview, and end view a family of wound drain assemblies of differinglengths that can be used in the manner shown in FIGS. 4A and 4B, e.g.,following reconstructive surgery.

FIGS. 23A, 23B and 23C are, respectively, a perspective top view, sideview, and end view a family of wound drain assemblies of differinglengths that can be used in the manner shown in FIGS. 4A and 4B, e.g.,following cosmetic surgery.

FIG. 24A shows an internal drain system comprising a serial, in-linearray of individual wound drain assemblies, each being like that shown,e.g., in FIGS. 22A/B/C.

FIG. 24B shows the series, in-line array of individual wound drainassemblies shown in FIG. 24A in use along the longitudinal axis of awound void, e.g., formed as a result of spinal fusion.

FIG. 24C shows the series, in-line array of individual wound drainassemblies shown in FIG. 24A in use in a wound void that extends atleast partially in an anterior and posterior, or circumferentialaspects, e.g., formed as a result of abdominoplasty.

FIG. 25A shows an internal drain system comprising a parallel, branchedarray of individual wound drain assemblies, each being like that shown,e.g., in FIGS. 22A/B/C.

FIG. 25B shows the parallel, branched array of individual wound drainassemblies shown in FIG. 24A in use in a wound void that extends atleast partially in an anterior and posterior, or circumferentialaspects, e.g., formed as a result of abdominoplasty.

FIGS. 26A to 26G show the installation of a wound drain assembly in anoperative dead. space or seroma site through a trocar.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention that may be embodied inother specific structure. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined by the claims.

FIG. 4 shows a wound drainage system 10 comprising an internal drainassembly 12 that is sized and configured for surgical placement within awound void W or body cavity). The wound void W may be anywhere in ahuman or animal, e.g., within a body cavity, or beneath the skin, or inmuscle, or within the soft tissues.

As shown in FIG. 4, the wound W can be defined as an interior dead spaceor void having a volume enclosed between interior tissue surfacesconsisting of muscle, connective, or skin tissue containing bloodvessels that have been separated by surgery or trauma within a bodybeneath substantially intact skin. As previously described,extracellular exudates comprising serous fluid, wound exudate, bloodcells, blood products, blood clots, thrombus, wound debris, dead cellsand other viscous materials—the byproducts of the wound healingprocess—escaping from the blood vessels can accumulate in the dead spaceand, if not removed, form a seroma.

As will be described in greater detail later (see also FIG. 6) , theinternal drain assembly 12 includes a housing 18. The housing 18comprises an inert, biocompatible, non-tissue adherent material, whichdoes not adhere to or activate the body's natural foreign body defensemechanism. The material can comprise, e.g., non-sticky or lubricatedsilicone rubber, polyurethane, or other biocompatible plastics. Thehousing 18 is sized and configured for placement entirely within theinterior dead space. The housing 18 can be formed. e.g., by extrusion,molding, or machining. As will be described in greater detail later, thehousing 18 can be formed in various shapes and sizes, depending upon therequirements and morphology of the wound site and function and use ofthe drain. In the configuration shown in FIG. 8, a representative sizemeasures about 5″ (length)×about ¾″ (width)×about ½″ (height).

The housing 18 may be impregnated or coated with bioactive agents, suchas silver, antibiotics, antibacterials, or growth factors, which maydecrease infection and promote wound healing. The housing 18 may alsoinclude other hormone or natural or manmade stimulating factors that candecrease the chance of infection and/or accelerate wound healing. Thehousing 18 can also be impregnated or coated with a bioactive agent suchad methotrexate.

The housing 18 is formed to include a hollow interior chamber 28, whichis enclosed by the side and end walls of the housing 18. The interiorchamber 28 encloses an open cell component 16. The open cell component16 is characterized in that it does not particulate in the presence offluid and pressure, and that it takes in, e.g., by adsorption and/orabsorption) the extracellular exudates found in an interior, surgicallycreated dead space. The open cell structure can comprise, e.g., gauze,or a foam sponge material comprising, e.g., an open-cell porousstructure (see FIG. 7A) or a granulated foam construction (see FIG. 7B)e.g., sponge materials in the 40 to 60 range pore size can be used, madeof polyurethane or various other nonreactive plastics that exist now ormay come into existence in the future. The open cell component 16 can bevariously constructed from a biocompatible material that does notactivate the body's natural foreign body defense mechanism.

The open cell component 16 is desirably compressible for easy insertioninto and removal from the housing 18 for replacement. The configurationof the housing 18 can also provide a contour facilitates sliding of theinternal drain assembly 12, easing removal from the body.

The open cell component 16 may also be impregnated with bioactive agentssuch as silver, or antibiotics, or antibacterials, or growth factors,which may decrease infection and promote wound healing. The open cellcomponent may also include other hormone or natural or manmadestimulating growth factors that can decrease the chance of infectionand/or accelerate wound healing. For wound drains installed followingcancer surgery, the open cell component 16 can also be impregnated orcoated with a bioactive agent such as methotrexate or otherchemotherapeutic agents.

In this arrangement, the housing 18 is also formed to include one ormore through-slots, through-apertures, or through-perforations 20 in theside and/or end walls of the housing 18. The through-slots,through-holes, or through-perforations open the hollow interior chamberto communication with the wound site environment outside the housing 18.The open cell component 16 communicates with the wound void W throughthe through-slots, through-apertures, or through-perforations 20 thatperforate the housing 18.

The through-slots, through-apertures, or through-perforations 20perforating the housing 10 are sized and configured to pass, withoutsubstantial plugging, the extracellular exudates comprising serousfluid, wound exudate, blood cells, blood products, blood clots,thrombus, wound debris, dead cells and other viscous materials, whichcan be expected to reside in the wound void W. In a representativeembodiment, the through-slots, through-apertures, orthrough-perforations 20 are sized and configured to present a mean porediameter of between about 0.5 mm to about 5 mm. Other desirable sizesand configurations for the apertures 20 will be described in greaterdetail later.

The materials conveyed through the through-slots, through-apertures, orthrough-perforations 20 into the open interior are taken in (e.g., byadsorption and/or absorption) by the open cell material 18.

As before described, the housing 18 comprises a non-tissue adherentcovering for the open cell component 16. This allows easy removal of theinternal drain assembly 12, because there is no departiculation oradherence of the open cell component 16 to the surrounding soft tissues.Due to the enclosure of the open cell component 16 within the non-tissueadherent housing 18, there is also no bleeding upon removal of theinternal drain assembly 12, because there is no sticking adherence ofthe internal drain assembly 12 to the soft tissues internally.

An end of a drain tubing 14 is coupled to the housing 18 and opens intothe hollow interior chamber 28. The drain tubing 14 is desirablyflexible and made of medical grade, inert material. e.g., siliconerubber, polyurethane, or other biocompatible plastics. The tubing isdesirably sized and configured to accommodate sufficient fluid flow witha relatively small and tolerable incision size (e.g., about 2-3″ indiameter).

The drain tubing 14 extends outside the wound void W. The drain tubing14 can extend through a percutaneous incision in the skin overlying anywound void W. Alternatively, the drain tubing 14 can extend through anopening in a skin flap bounding the wound void. The flexible draintubing 14 includes a terminal end 22 that extends outside the body.

The terminal end 22 desirably includes a quick release connector 24. Theconnector 24 is sized and configured to be connected to a conventionalexternal negative pressure suction device 26 (such as a V.A.C.® devicemade by KCI International, or a conventional wall suction or otherregulated vacuum device).

In use (as FIGS. 4A and 4B show), the drain tubing 14 is connected tothe suction device 26. The suction device 26 is operated to apply arequisite negative pressure through the internal drain assembly 12. Theextracellular exudates comprising serous fluid, wound exudate, bloodcells, blood products, blood clots, thrombus, wound debris, dead cellsand other viscous byproducts of the wound healing process thataccumulate in the wound cavity (as previously described), are taken in(e.g., by adsorption and/or absorption) by the open cell component 16.Concurrently, the extracellular exudates comprising serous fluid, woundexudate, blood cells, blood products, blood clots, thrombus, wounddebris, dead cells and other viscous materials of the wound healingprocess are drawn by the negative pressure through the open cellcomponent 16 from the wound void W.

The drain tubing 14 desirably includes an inline reservoir 30 to collectthe withdrawn extracellular exudates comprising serous fluid, woundexudate, blood cells, blood products, blood clots, thrombus, wounddebris, dead cells and other viscous byproducts of the wound healingprocess for disposal.

As FIG. 5 shows, occupying the interior of the wound void F, theinternal drain assembly 12 conveys negative pressure throughout theentire open volume of the wound space. The negative pressure applied bythe internal drain assembly 12 clears the extracellular exudatescomprising serous fluid, wound exudate, blood cells, blood products,blood clots, thrombus, wound debris, dead cells and other viscousbyproducts of the wound healing process from the entire wound volume. AsFIG. 4B also shows, the removal of these materials from the entire woundvolume promotes tissue adherence within the wound void, to close thewound void and seal the wound.

The internal drain assembly 12 makes possible the placement of theperforated, non-tissue adherent housing 18 enclosing the large surfacearea of the open cell component 16 entirely within the interior woundvoid or dead space, with the drain tubing 14 extending from the interiorwound void or dead space through a percutaneous access to a locationoutside the body, as FIG. 4A shows. The drain tubing 14 can be coupledto a source of negative pressure outside the body, and the source ofnegative pressure operated to convey negative pressure into the openinterior of the housing for application through the perforationsinternally throughout the interior wound void or dead space (as FIGS. 4Band 5 show). The internal drain assembly 12 makes possible, in responseto the applied negative pressure, the conveyance of the extracellularexudates comprising serous fluid, wound exudate, blood cells, bloodproducts, blood clots, thrombus, wound debris, dead cells and otherviscous byproducts of the wound healing process taken in (e.g., byadsorption and/or absorption) by the open cell component 18 from theinterior wound void or dead space to decrease the volume of the woundvoid or dead space and subsequent seroma formation. The internal drainassembly 12 makes possible, in response to the applied negativepressure, the drawing together of the separated interior tissue surfacesto promote adherence of the tissue surfaces and a normal wound healingprocess, as FIG. 4E shows.

The negative pressure can be, e.g., 75 mmHg to 200 mmHg, and isdesirably about 125 mmHg below ambient pressure, although the negativepressure may fail slightly above that range and may also decrease belowthat range over time. The amount of negative vacuum pressure can beregulated in a continuous, discontinuous, or otherwise variable manner,to maximize wound healing and closure. In this way, the system 10promotes primary wound healing while also decreasing or minimizingseroma formation. The pressure required to keep the tissues approximatedmay also decrease over time and fall to the negative 20 mmHg to 100 mmHgrange.

As FIGS. 16 and 17 show, the introduction of negative pressure into thehousing 18 can cause the housing 18 itself to collapse against the opencell component 16 (as FIG. 17 shows). However, the through-perforations20 of the housing 18 maintain open paths for fluid to be taken in (e.g.,by adsorption and/or absorption.) by the open cell component 16. TheExample that follows demonstrates that this, in fact, occurs in aninterior wound environment.

As FIGS. 4A/B and 5 show, the drain tubing 14 desirably includes aninline one-way backflow valve V. The one-way backflow valve V allowsfluid to be drawn from the wound volume into the reservoir 30. Upondisconnection of the drain tubing 14 from the external negative pressuresuction device 26 (via the connector 24), the one-way backflow valve Vprevents air or fluid to flow backward into the wound or body. Theone-way backflow valve V keeps the internal drain assembly 12 closedwhen not connected to the external negative pressure suction device 26.

As FIGS. 9 to 13 show, the housing 18 can be formed in variousdimensions, shapes, and sizes, and the open cell component 16 cut tocorresponding dimensions, shapes, and sizes. These dimensions, shapes,and sizes can comprise, e.g., square (FIG. 9); oval (FIG. 10); hexagonal(FIG. 11); round (FIG. 12); or rectangular (FIG. 13); or any linear orcurvilinear shape or combinations thereof. The ends of the housing 18can be tapered or not tapered (as FIGS. 9 to 13 demonstrate). Thethrough-perforations 20 can also be variously shaped and sized (as FIGS.9 to 13 demonstrate). The through-perforations 20 can also be tapered ornot tapered along their axes. The perforations 20 can form an array ofapertures substantially around the entire periphery of the housing 18,or the apertures can be confined to one surface or a portion of asurface of the housing 18.

A further representative embodiment is shown in FIGS. 20A and 20B. Inthis embodiment, the housing 18 is generally circular in cross section,enveloping the open cell component 16. The drain tubing 14 extends intothe open cell component 16 for substantially the entire length of thehousing 18. Spaced-apart ports P are formed along the extension of thedrain tubing 14 within the open cell component 16, through whichnegative pressure is uniformly distributed into the housing 18. Thedistal end of the drain tubing 14 is sealed within the distal tip 22 ofthe housing 18.

As shown in FIGS. 20C/D, the through-perforations 20 can take the formof slots or slits 32 that are sized and configured to emulate a one-wayvalve.

For example, as shown in FIGS. 20C/D, each perforation can comprise apattern of: crossing slots or slits 32, forming an “x.” The “x” slitforms four leaflets 34 of a valve. In the absence of negative pressure(see FIG. 20B), the leaflets 34 of the crossing slots or slits 32 aregenerally coplanar, forming a normally, substantially “closed” valveconfiguration. The substantially normally closed valve configurationprevents tissue in-growth into the open cell component 16. However, whennegative pressure is applied by the drain tubing 14 within the housing18 (see FIG. 20B), the leaflets 34 are mutually drawn inward in responseto the negative pressure (i.e., mutually drawn toward the negativepressure applied to the open cell component 16), forming an “opened”valve configuration. The opened valve configuration passes theextracellular exudates comprising serous fluid, wound exudate, bloodcells, blood products, blood clots, thrombus, wound debris, dead cellsand other viscous byproducts of the wound healing process from theinterior wound void or dead space into the open cell component 16,without substantial plugging, to decrease the volume of the wound voidor dead space and subsequent seroma formation.

Another representative emulation of a one way valve is shown in FIGS.21A/B/C. In this embodiment, each perforation comprises a slot or slit32 forming a semilunar flap in the housing 18. In the absence ofnegative pressure (see FIG. 21B), flap forms the leaflet of a normallysubstantially “closed” valve configuration. The normally substantiallyclosed valve configuration prevents tissue in-growth into the open cellcomponent 16. However, in the presence of negative pressure (see FIG.21B), the leaflet 36 is drawn inward in response to the negativepressure applied by the drain tubing 14 within the open cell component16 (i.e., drawn toward the open cell component 16), forming an “opened”valve configuration. The opened valve configuration passes theextracellular exudates comprising serous fluid, wound exudate, bloodcells, blood products, blood clots, thrombus, wound debris, dead cellsand other viscous byproducts of the wound healing process from theinterior wound void or dead space into the open cell material, todecrease the volume of the wound void or dead space and subsequentseroma formation.

By way of example, the pore size can range between 0.5 mm to 5 mm, andthe separation between pores can be, e.g. about 8 mm, although themagnitudes can vary upward or downward.

As before described, the internal drain assembly 12 as described can beinserted through relatively small and tolerable percutaneous incisionsize (e.g., about 2-3″ in diameter).

Furthermore, as shown in FIGS. 26A to 26E, the internal drain assembly12 can be sized and configured for insertion through a cannula ortubular sleeve 38 (which can also be called a “trocar”) made, e.g., of arigid plastic or metallic material. The cannula has an open interiorbore 40 and a penetrating distal tip 42 (see FIG. 26A). The tip 42 ofthe cannula incises or separates tissue when the cannula 38 is axiallyadvanced into tissue (typically through an initial incision), to allowadvancement of the distal end 42 of the cannula 38 into the operativedead space or seroma site W (see FIG. 26B). The open interior bore 40 ofthe cannula 38 provides an access path or lumen into the operative deadspace or seroma site W.

In a representative embodiment, the bore 40 of the cannula 28 comprisesah interior diameter of, e.g., 4.5 mm, and the housing 18 of theinternal drain assembly is sized and configured (e.g., outside diameterof about 3 mm) for insertion thorough the proximal end of cannula 38 andadvancement though the bore 40 (see FIG. 26C). The housing 18 can, ifdesired, be lubricated (wetted) for passage through the bore 40.

The housing 18 is pushed distally (i.e., advanced axially), until thehousing 18 rests at distal tip 42 of cannula 38. The cannula 38 iswithdrawn (retracted) while holding internal drain assembly 12stationary (see FIG. 26D). This places the housing 18 of the internaldrain assembly 12 in communication with the operative dead space orseroma site W (see FIG. 26E), where it can serve to remove extracellularexudates comprising serous fluid, wound exudate, blood cells, bloodproducts, blood clots, thrombus, wound debris, dead cells and otherviscous byproducts of the wound healing process, to decrease the volumeof the operative dead space and subsequent seroma formation at the site.

The housing 18 can be formed in different dimensions, shapes, and sizes,and the open cell component 16 cut to corresponding dimensions, shapes,and sizes, to create different families of wound drains sized andconfigured to meet the particular requirements of a given surgicalprocedure or class of surgical procedures.

For example, as shown in FIGS. 22A/B/C, a family 44 of wound drains12(1), 12(2), and 12(3) can be sized and configured with a similar ovalcross section profile, but in different lengths, to serve as a family 44of wound drains 12(1), 12(2), and 12(3) useful, e.g., afterreconstructive surgery. Each wound drain assembly 12(1), 12(2), and12(3) includes a perforated housing 18 enclosing an open cell component16 through which negative pressure is applied. A. representative ovalcross section profile for a reconstructive drain family 44 can be, e.g.,15 mm by 10 mm. Representative lengths for the reconstructive drainfamily can range, e.g., from 10 mm to 200 mm.

As another example, as shown in FIGS. 23A/B/C, a family 46 of wounddrains 12(4), 12(5), and 12(6) can be sized and configured with asimilar circular cross section profile but in different lengths, toserve as a family 46 of: wound drains 12(4), 12(5), and 12(6) useful,e.g., after cosmetic surgery. Each wound drain assembly 12(4), 12(5),and 12(6) includes a perforated housing 18 enclosing an open cellcomponent 16 through which negative pressure is applied. The crosssection profile and lengths of the cosmetic drain family 46 are shown tobe smaller than those of the reconstructive drain family, because, dueto the anatomy of the surgical site, cosmetic surgery typically formssmaller, more compact wound voids than reconstructive surgery. Arepresentative circular cross section profile for a cosmetic drainfamily 46 can be, e.g., 8 mm. Representative lengths for the cosmeticdrain family can range, e.g., from 10 mm to 150 mm.

Another representative embodiment is shown in FIG. 24A. In thisembodiment, an internal drain system 10 can comprise a serial array ofindividual, in-line wound drain assemblies 12, which are coupledserially by flexible intermediate lengths of drain tubing 14. Each wounddrain assembly 12 includes a perforated housing 18 enclosing an opencell component 16 through which negative pressure is applied. In use,the in-line internal drain system 12 can be placed, depending upon themorphology of a given wound void, along the axis of a longitudinallyelongated wound void (e.g., as a result of spinal fusion surgery) (see,e.g., FIG. 24E), or from front to back within a wound void that extendsat least partially in anterior and posterior, or circumferential,aspects (e.g., as a result of abdominoplasty or total joint replacementsurgery) (see, e.g., FIG. 24C), or a wound site that requires, e.g.,drainage both inside and outside the abdomen.

Another representative embodiment is shown in FIG. 25A. In thisembodiment, an internal drain system 50 can comprise a parallel orbranched array of individual wound drain assemblies 12, which is coupledin parallel branches from a main drain tube 14 by flexible intermediatelengths 52 of drain tubing. Each wound drain assembly 12 includes aperforated housing 18 enclosing an open cell component 16 through whichnegative pressure is applied in use, the parallel internal drain system50 can be placed from front to back within a wound void that extends atleast partially in anterior and posterior, or circumferential, aspects(e.g., as a result of abdominoplasty or total joint replacement surgery)(see, e.g., FIG. 25B), or a wound site that requires, e.g., drainageboth inside and outside the abdomen.

Any given wound drainage system 10, 48, 50 can be variously configuredand assembled. For example, as shown in FIG. 14, the in-line reservoir30 is intended, in use, to be placed at a gravity position at or belowthe drain assembly 12 and includes separate fluid inlet and vacuumoutlet paths arranged along the top of the reservoir 20, coupled,respectively, to the internal drain assembly 12 and. the externalnegative pressure suction device 26. As FIG. 15 shows, the reservoir 30is intended, in use, to be placed at a gravity position above the drainassembly 12 and includes an fluid inlet path arranged along the bottomof the reservoir 30 (coupled to the drain assembly 12) and a vacuumoutlet port arranged along the top of the reservoir 30 (coupled to theexternal negative pressure suction device 26).

As FIG. 18 shows, the system 10 may include a battery powered externalnegative pressure suction device 26′ that can be carried by theindividual. The system 10 can therefore be operated while the individualambulates, so that the individual need not be bed-bound during therecovery period.

As shown in FIG. 19A, a internal drain assembly 56 can comprise a meshstructure 54 coupled to the tubing 14 comprising a material that isbioabsorbable, meaning that it transforms over time within the woundvolume from a solid state to a state that can be cleared or absorbed bythe body. The absorbable material of the mesh structure can be made ofsterile material, such as, e.g., Vicryl, moncryl, PDS, polyvinylalcohol, polyurethane, or animal or human tissue, or other absorbablematerial that could be woven into a foam-like construct. In thisarrangement, the internal drain assembly 56 can also include aperforated housing 18 made of an absorbable material, which encloses theabsorbable mesh structure 54.

In this embodiment, when the internal drain assembly 56 has completedits job (see FIG. 19B), the silicone or plastic tubing 14 is detachedfrom absorbable mesh structure 40 (or the absorbable housing 18enclosing the absorbable mesh structure) and removed, leaving theabsorbable mesh structure 54 (or housing and absorbable mesh structure)inside the body, to dissolve and absorb just like absorbable suture, asshown in FIG. 19C.

EXAMPLE

Wound drain assemblies having the technical features described abovewere placed into internal wound voids surgically created in a porcinemodel. Also concurrently placed into surgical created wound voids in thesame porcine model were conventional wound drains. The performance ofefficacy of the wound drain assemblies were compared to the performanceand efficacy of the conventional drains over a period of eight days.

More particularly, following induction of general anesthesia, prefascialpockets were elevated with scissor dissection through ten (10) cmincisions on left and right lateral sides of a pig over the latissimusdorsi muscles and external oblique muscles, just posterior to the frontlegs. The left and right side pockets were placed six (6) cm off themidline to assure the pockets were kept separate. Bovie cautery was usedfor hemostatsis and pockets were irrigated with a triple antibioticsolution used in implant surgery, comprising 1 gm of Ancef, 80 mg ofGentamicin, and 50,000 IU units of Bacitracin/500 cc NS.

Conventional Silastic Blake Drains (Ethicon, Inc., a Johnson & JohnsonCompany; Somerville, N.J.) were placed through the incisions into thesubcutaneous pocket on the animal's left side. The Blake Drains (15 mmin diameter) were identical to those used clinically in practice inhumans.

A wound drain assembly, like that shown in FIGS. 21 A/B/C (with a foamsponge component 16 and semilunar slits 32 perforating the housing)(hereafter, in shorthand, the “WDA”), was placed in the tripleantibiotic solution, and then placed into the subcutaneous pocket on theanimal's right side.

Closure was performed in multiple layers on both sides with additionalPDO Quill™ closure (Angiotech Pharmaceuticals), Dermabond® liquid skinadhesive (Ethicon, Inc., a. Johnson & Johnson Company; Somerville, N.J.)applied to the skin, and Opsite® Post-Op waterproof dressings (Smith &Nephew), for a complete water tight seal at the operative sites.

Standard suction bulbs were placed on the Blake Drains to mimic currentclinical usage.

A portable negative pressure V.A.C. pump (NCI), set to deliver astandard 125 mmHg of suction pressure, was coupled to the WDA to apply auniform continuous suction in the wound void throughout the course ofthe study.

The animal was dressed in a specially designed post-surgical vest, withzippered pockets worn on the animals' backs. The drains were brought outof separate incisions beneath the vest and into a zipper pockets on thevest.

The same set up of a Blake Drain and a WDA was performed on a secondpig, with a standard Blake Drain on the left side and the WDA on theright side.

The pigs did very well postoperatively. The drains remained intactattached to the animals and carried within the specially designed jacketpockets worn on the animals' backs. The animals received antibioticsdaily and all wound pockets healed well with no infection.

The suction bulbs (on Blake Drains) and pumps (on the WDA's) werechecked every four hours for the first twenty-four hours, every eighthours for the next three days, and then every twelve hours to completionof the study (on day 8). The dressings were changed, fluid recorded,bulbs recharged and canisters changed. The drain canisters were changedat the above schedule during animal feedings, and they tolerated thechanges very well while they were feeding.

The canisters were weighed per-placement and weighed. on removal. Thedrainage recorded from the animals is as follows:

Blake Drain WDA Pig 1 200 cc over 8 days 170 gm over 8 days (1 gm is ~=1cc fluid) Pig 2 400 cc over 8 days 180 gm over 8 days

The following observations were made:

i) Over 80% of the WDA drainage occurred in the first 24 hours. Incontrast, drainage on the standard drain side remained constantthroughout the study period.

(ii) The exudates of the standard Blake Drains remained bloody andviscous throughout the study. In contrast, the exudates of the WDA had aquicker return on day 3 from bloody and viscous to a serum-straw coloredfluid.

Following eight days of drain placement, the animals were brought backto surgery, and the wound voids were evaluated. The incisions had healedwell and there was no evidence of infection.

Both Blake Drains had healed directly around the wound voids. However,the wound voids had not closed completely. As is typically experiencedin human clinical situations, both of the Blake Drain sites in theporcine model had peripheral seroma pockets in the prior surgicalspaces.

Both WDA's had complete closure of the prior surgical spaces around theentire periphery of the wound void, up to the point of the WDA itself.It was difficult to redevelop and finger fracture this space back open.Biopsy specimens show complete closure of the surgical space andhealing.

Neither WDA had absolutely any adherence to the soft tissues, and therewas no fragmentation of any open cell material in the surgical space.There was mild imprinting in the pocket where the WDA was located. (thiswas also visualized on the Blake Drain side). The pocket surrounding theWDA was small, snug and tight, and just slightly larger than the WDAitself. There continued excellent flow through the WDA through the 8thday. Forces to remove the WDA were reasonably low.

The foregoing Example demonstrates that wound drain assemblies havingthe technical features described herein function very well, serving asan internal wound closure device to effectively close a large surgicallycreated space. The entire surgical space was completely occluded andhealed down to a pocket just surrounding the wound drain assemblyitself, to the point it was very difficult to open the surgical spaceback up. There was no adherence or departiculation of the open cellmaterial in the surgical space. The semilunar flaps performed well,maintaining easy and complete flow through them on suction, but notallowing any ingrowth or adherence of the assembly. Eighty percent (80%)of the fluid removed with the wound drain assembly occurred in the firstday, then tapered off dramatically, with the exudates turningstraw-colored on the third day.

The foregoing Example demonstrates that peripheral seroma cavitiesoccurred in both animals with standard Blake Drains and bulbs, mimickingwhat occurs clinically in humans, where seroma cavities remain problemsand the soft tissues often do not come together to allow approximationand healing through the natural body processes greater flow volumescontinued throughout the study, with the evacuates remaining very bloodyin the standard Blake Drain groups.

The Example demonstrates that applying a vacuum of significant pressureinternally and directly in a wound void or body cavity using a wounddrain assembly as disclosed herein results in the relatively quick andeffective removal of the extracellular exudates comprising serous fluid,wound exudate, blood cells, blood products, blood clots, thrombus, wounddebris, dead cells and other viscous byproducts of the wound healingprocess from the interior wound void, without substantial plugging, aswell as results in an enhanced formation of tissue adherence and wouldhealing. Applying a vacuum of significant pressure internally anddirectly in a wound void or body cavity using a wound drain assembly asdisclosed herein accelerates healing by the application of a universalnegative force to the entire wound volume, drawing the wound edgestogether, assisting closure, enhancing wound healing, and decreasingdead space and seroma. Applying a vacuum of significant pressureinternally and directly in a wound void or body cavity using a wounddrain assembly as disclosed herein brings about beneficial changes tothe surgical site, including changes in microvascular blood flowdynamic; changes in interstital fluid; the removal of wound exudates;the stimulation of growth factors and collagen formation; the reductionin bacterial colonization; the mechanical closure of wound by “reversetissue expansion;” increased adherence of the soft tissue and internalwound healing; and decreased dead space and seroma formation.

The invention provides assemblies, systems, and methods that not justmanage blood and fluid collection in an internal wound cavity, but alsoclose and eliminate the dead. interior space, drawing the separatedinterior tissue surfaces together to promote adherence of the tissuesurfaces and a normal wound healing process.

The foregoing is considered as illustrative only of the principles ofthe invention. Furthermore, since numerous modifications and changeswill readily occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and operation shown anddescribed. While the preferred embodiment has been described, thedetails may be changed without departing from the invention, which isdefined by the claims.

1-36. (canceled)
 37. A drain system, comprising: a branched array thatincludes a plurality drain assemblies configured to be inserted into avolume within a body, each drain assembly including a housing having: anopen interior; and at least one perforation; and a main tube configuredto couple to a source of negative pressure and communicate with thebranched array, such that negative pressure from the source of negativepressure is conveyed to the open interiors of the plurality of drainassemblies, wherein the at least one perforation is configured suchthat, in a presence of the negative pressure in the open interior,matter accumulated in the volume within the body passes through the atleast one perforation and into the open interior.
 38. The drain systemof claim 37, wherein the plurality of drain assemblies are furtherconfigured such that the presence of the negative pressure in the openinteriors of the plurality of drain assemblies draws and holds togetherinternal tissue forming the volume within the body.
 39. The drain systemof claim 37, wherein the plurality of drain assemblies are furtherconfigured such that the presence of the negative pressure in the openinteriors of the plurality of drain assemblies reduces a size of thevolume within the body.
 40. The drain system of claim 37, wherein: thebranch array is removable from the plurality of drain assemblies, suchthat the branch array and main tube are removable from the body; and theplurality of drain assemblies consist of material that is absorbable bythe body.
 41. The drain system of claim 40, wherein at least a portionof the material of the plurality of drain assemblies is at least one ofimpregnated or coated with a bioactive or chemotherapeutic agent. 42.The drain system of claim 41, wherein the agent includes one or more ofa hormone, a growth factor, an antibiotic, or an antibacterial.
 43. Thedrain system of claim 37, further comprising: the source of negativepressure, wherein the source of negative pressure is configured to applythe negative pressure to the main tube.
 44. The drain system of claim43, wherein the source of negative pressure is portable.
 45. The drainsystem of claim 37, further comprising: a tubular sleeve including: abore configured to pass the housing of a drain assembly; and atissue-penetrating distal tip forming an end of the bore; wherein thetubular sleeve is configured to provide access to the volume within thebody and enable deployment of the plurality of drain assemblies therein.46. The drain system of claim 37, wherein each of the plurality of drainassemblies further includes an open cell component positioned within theopen interior of the housing, and configured to take in the matteraccumulated in the volume within the body that passes through the atleast one perforation and into the open interior. Application No.:Attorney Docket No.: 00181-0003-02000
 47. A method of treating a body,comprising: deploying a branched array that includes a plurality ofdrain assemblies into a volume within the body; operating a source ofnegative pressure to apply a negative pressure to an open interior ofrespective housings of the plurality of drain assemblies, wherein: thenegative pressure is applied via a main tube coupled to the source ofnegative pressure and to the branched array; and each of the respectivehousings has a plurality of perforations at least one perforation thatprovide provides communication between the open interior of the housingand the volume within the body.
 48. The method of claim 47, furthercomprising: via the negative pressure in the plurality of drainassemblies, drawing and holding together internal tissue forming thevolume within the body.
 49. The method of claim 47, further comprising:via the negative pressure in the plurality of drain assemblies, reducinga size of the volume within the body.
 50. The method of claim 47,further comprising: via the negative pressure in the plurality of drainassemblies, drawing matter accumulated in the volume within the bodythrough the at least one perforation pluralities of perforations andinto the open interiors of the plurality of drain assemblies.Application No.: Attorney Docket No.: 00181-0003-02000
 51. The method ofclaim 47, further comprising: inserting at least one housing of theplurality of drain assemblies into a bore of a tubular sleeve; advancinga penetrating distal tip of the tubular sleeve into the volume of thebody; advancing the at least one housing to the penetrating distal tip;holding the at least one housing in place, and withdrawing the tubularsleeve to deploy the at least one housing into the volume of the body.52. The method of claim 47, wherein, after the plurality of drainassemblies are deployed, the main tube passes from within the body tooutside of the body.
 53. The method of claim 47, further comprising:decoupling the plurality of drain assemblies from the branched array;and removing the main tube and the branched array.
 54. The method ofclaim 53, wherein: the plurality of drain assemblies consist of materialthat is absorbable by the body; and the method further comprisesallowing the plurality of drain assemblies to be absorbed by the body.Application No.: Attorney Docket No.: 00181-0003-02000
 55. The method ofclaim 47, wherein: the plurality of drain assemblies include materialthat is at least one of coated or impregnated with a bioactive orchemotherapeutic agent; and the method further comprises delivering theagent to the body via the plurality of drain assemblies.
 56. A treatmentsystem, comprising: a branched array that includes a plurality of drainassemblies configured to be inserted into a volume within a body, eachdrain assembly formed from material that is absorbable by the body andincluding a housing having: an open interior; and a plurality ofperforations at least one perforation; and a main tube configured tocouple to a source of negative pressure and communicate with thebranched array, such that negative pressure from the source of negativepressure is conveyed to the open interiors of the plurality of drainassemblies, wherein the plurality of drain assemblies are furtherconfigured such that a presence of the negative pressure in the openinteriors of the plurality of drain assemblies draws and holds togetherinternal tissue forming the volume within the body and at leastpartially closes the volume; and wherein the main tube is removable fromthe plurality of drain assemblies.